The present invention relates to transdermal and/or intradermal drug delivery devices, kits and methods and, more particularly, to a dermal patch which is capable of delivering an electric current for electrically including transdermal and intradermal delivery of a wide variety of substances or for enhancement of wound healing, scar prevention, scar reduction, tissue repair and/or tissue regeneration via electrical stimulation.
Much recent attention has been paid in the technical and patent literature to the delivery of substances, both pharmaceuticals and cosmetics, such as drugs and other beneficial agents, into or through intact skin surfaces by passive processes such as diffusion and osmosis and by active processes such as electrically induced iontophoresis, electrophoresis, electroosmosis and/or electroporation. The ubiquitous nicotine patch designed to assist in quitting smoking has caused such forms of transdermal delivery of medication to be widely known. (Hereunder, the term “iontophoresis” will collectively represent any of the terms iontophoresis, electrophoresis, electroosmosis and/or electroporation, and the term “iontophoretic” will encompass the respective adjectives.)
Indeed, there is now an extremely long list of pharmaceutical substances that are routinely administered transdermally and/or intradermally and a similarly long list of devices and methods known in the art for administering same. A short but varied sampling includes the following: U.S. Pat. No. 6,294,582 which discloses a device for treating asthma transdermally; U.S. Pat. No. 5,899,856 which discloses a dermal patch for detecting alcohol consumption; U.S. Pat. No. 6,291,677 which teaches the transdermal administration of antiviral protease inhibitors; U.S. Pat. No. 6,266,560 which discloses the transdermal treatment of erectile dysfunction; U.S. Pat. No. 6,238,381 which discloses the transdermal delivery of antiviral, antibacterial and antiaging substances; and U.S. Pat. No. 6,288,104 which discloses the transdermal administration of substances for treating congestive heart failure.
Although many substances are administered passively via a dermal patch, there are also many that are electrically delivered intradermally or transdermally.
The use of electrical stimulus to body parts is well known and has an equally long and colorful history. Around the turn of the 20th century there was available a plethora of “electrodes” for applying “electric treatments” to the human body. The electrodes were placed upon the body in relation to the organ to be treated. Such early “electric treatments” included popular galvanic stimulation which caused ionized molecules to be driven into the body, usually superficially. This early form of iontophoresis, or ion transfer, was employed for the supposed beneficial effects of localized stimulation and the introduction of medicaments, often simply moisture, into the skin of a patient.
The technique of iontophoresis is in wide use today in the administration of drugs as it effectively delivers electrically charged medicaments through the skin, and into the capillary structure and lymphatic system. This technique avoids the gastrointestinal side effects sometimes associated with orally ingested drugs and is preferable to subcutaneous injection because of its relatively benign and painless nature.
Another technique, known as electroporation, facilitates the transdermal or intradermal delivery of uncharged substances by electrically inducing the formation of transient dermal micropores that allow mobilization of the uncharged substances by diffusion.
Accordingly, iontophoresis, as well as other electrically induced techniques, such as electroporation, has been incorporated into many transdermal delivery devices, including the popular dermal patch. Therefore, there are many dermal patches known in the art today which incorporate a power source and electrical circuitry for aiding transdermal delivery.
Most present dermal patches, including those that function passively and those that function electrically, incorporate a substance for transdermal delivery. Such patches are specifically designed and/or configured to deliver a predetermined dosage of a specific substance, and that substance forms an integral part of the patch in question, i.e., the “nicotine patch”. One drawback of such dermal patches, which are manufactured with a predetermined type and amount of substance therein is that once the substance is depleted, the entire device is useless and must be discarded. This is a disadvantage because patches which employ electrically induced delivery techniques necessarily have components, e.g., batteries, electrodes, circuitry and other assemblies, which may be expensive and/or environmentally hazardous when discarded in large quantities. Also, in order to change dosage, patches of different dosages must be provided.
There is also known in the art today a range of reusable dermal patches that incorporate a reservoir for holding a medicinal substance prior to administration. Those dermal patches typically incorporate the reservoir as part of one or both of the electrodes which deliver the current to the skin of the subject. Such electrodes are often referred to as bioelectrodes.
Bioelectrodes come in many sizes, shapes and configurations such as the following assigned to Ioimed, Inc., which produces iontophoretic delivery devices. Examples of such bioelectrodes include those disclosed in U.S. Pat. Nos. 5,037,380 and 5,248,295 which teach a patch having a refillable receptacle; U.S. Pat. No. 5,846,217 which teaches a patch having a small access window for refilling; and U.S. Pat. Nos. 5,374,245, 5,730,716 and 6,223,075 which teach a patch that holds a dry medicament and must be hydrated. All such bioelectrodes are complex and consist of many parts and are therefore relatively bulky. Accordingly, those that are incorporated into dermal patches cause the patches to be large and relatively expensive. Moreover, such dermal patches must be charged, or loaded, by a clinician and not by the subject.
There is thus a widely recognized need for, and it would be highly advantageous to have, a thin, flexible and simple electrically active dermal patch that is simple to administer by the subject, versatile and capable of application with a range of substances and/or dosages and for a variety of purposes and that is simple in design and inexpensive to manufacture.